A typical method of constructing a building begins with the following four steps in this order: (i) excavate the building site and lay the foundations; (ii) pour concrete floors; III construct the framing; and (iv) put the roof on.
It is desirable to have the roof constructed as quickly as possible to ensure the building is weathertight and further construction work can be undertaken inside the building. However, the distance between the ground and the roof of even a one-storey building is such that it is a legal requirement in many countries to put up scaffolding and/or other fall prevention mechanisms to ensure the safety of workers constructing the roof.
Scaffolding can be expensive and the time taken to install it can delay the construction of the roof. Additionally, the roofing materials used in the construction of the roof need to be lifted from the ground to the workers on the scaffolding, for example, by hand or via a pulley. This can also delay the construction of the roof.
U.S. Pat. No. 4,955,174 describes a building construction method in which a roof is constructed on the ground before being lifted by crane onto the top of a building frame and connected to the frame. Although this removes the need for scaffolding, a crane requires an experienced operator and sufficient room to swing the crane and room on site to build the roof. Accordingly, a crane can be expensive to operate and is not always suitable.
It is an object of the invention to provide a method of constructing a building and a lifting device for use in performing the method which will overcome the abovementioned difficulties or disadvantages.